TextComponents: fixed too fast scrolling in multi-line text component…

…s when using touchpads (e.g. on macOS) (issue #892)

CHANGELOG.md

@@ -9,6 +9,8 @@ FlatLaf Change Log
   using custom component that overrides `Component.contains(int x, int y)` and
   invokes `SwingUtilities.convertPoint()` (or similar) from the overridden
   method. (issue #878)
+- TextComponents: Fixed too fast scrolling in multi-line text components when
+  using touchpads (e.g. on macOS). (issue #892)
 - ToolBar: Fixed endless loop if button in Toolbar has focus and is made
   invisible. (issue #884)
 

flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatScrollPaneUI.java

@@ -210,7 +210,7 @@ private void mouseWheelMovedSmooth( MouseWheelEvent e ) {
 
 			// Use (0, 0) view position to obtain a constant unit increment of first item.
 			// Unit increment may be different for each item.
-			Rectangle visibleRect = new Rectangle( viewport.getViewSize() );
+			Rectangle visibleRect = new Rectangle( viewport.getExtentSize() );
 			unitIncrement = scrollable.getScrollableUnitIncrement( visibleRect, orientation, 1 );
 
 			if( unitIncrement > 0 ) {